Index for Section 5

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EvmCallback(5)
NAME
  EvmCallback - Event Management callback function

SYNOPSIS
  void EventCB(
	  EvmConnection_t connection,
	  EvmCallbackArg_t callbackArg,
	  EvmCallbackData_t *callbackData)

DESCRIPTION
  An EVM callback function is a function that you provide to allow your
  program to handle messages arriving on an EVM connection.  Most messages
  will be incoming events or responses to requests you have made to the EVM
  daemon, but you may also get a callback for other reasons.

  You specify the name (EventCB) of the callback function in the callback
  parameter when you create an EVM connection with a response mode of
  callback.

  Your callback function is invoked by EvmConnDispatch(), which you must call
  whenever you detect activity pending on the connection.

  An EVM callback function must conform to the prototype shown.

  Callback function parameters:

    ·  The connection parameter contains the connection context pertaining to
       this callback.  This value was returned by EvmConnCreate() when the
       connection was created. If you have one callback function servicing
       multiple connections, you might test this to determine which
       connection a particular invocation is handling.

    ·  The callbackArg parameter contains the value you specified as the
       callbackArg parameter to EvmConnCreate() when you created the
       connection. For example, you might use it to hold a pointer to your
       own context data for the connection.

    ·  The callbackData parameter points to a structure containing the
       details of the callback.	 The structure includes a callback reason
       code, an event, and a union containing data specific to each possible
       reason.	The event member may contain NULL if it is not applicable to
       the reason.  You may get these reasons:

       EvmREASON_EVENTS_MISSED
	   This callback reason indicates that the daemon was unable to
	   deliver one or more events, probably because the client process
	   had not finished processing earlier events, causing the connection
	   buffer to overflow.	If necessary, you can use EvmConnControl(3)
	   to increase the size of the receive buffer.

       EvmREASON_EVENT_DELIVERED
	   This callback reason indicates that an EVM event has been received
	   from the daemon. The event is available in the callbackData
	   structure.  You must use EvmEventDestroy(3) to free the event when
	   you have finished with it.

       EvmREASON_POST_COMPLETE
	   This callback reason indicates that a prior EvmEventPost() call
	   has completed, usually with a response from the daemon if the
	   responseMode was specified as EvmRESPONSE_CALLBACK when the
	   connection was created. The posting status is available in the
	   callbackData structure.

       EvmREASON_REGISTRATION_DELIVERED
	   This callback reason indicates that a requested template has been
	   delivered in response to an EvmConnRegistrationGet() request. You
	   must use EvmEventDestroy(3) to free the template when you have
	   finished with it.

       EvmREASON_SUBSCRIBE_COMPLETE
	   This callback reason indicates that a prior EvmEventSubscribe()
	   call has completed, usually with a response from the daemon.

       EvmREASON_TEMPLATE_INFO_DELIVERED
	   This callback reason indicates that event template information has
	   been delivered in response to an EvmConnTemplateScan() request.
	   The template is available in the callbackData structure. You must
	   use EvmEventDestroy(3) to free the template when you have finished
	   with it.

  See the Common Desktop Environment: Programmer's Guide for examples of
  callback functions.

FILES
  /usr/include/evm/evm.h
      Header file that contains the event declaration, structures, and
      prototype for the callback function

SEE ALSO
  Routines: EvmConnCreate(3), EvmConnCheck(3), EvmConnSubscribe(3),
  EvmEventPost(3)

  Event Management: EVM(5)

  Event Connection: EvmConnection(5)

  EVM Events: EvmEvent(5)

  Programmer's Guide

Index for Section 5

Alphabetical listing for E

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